The cost to inspect and repair faulty steam generators at the San Onofre nuclear plant reached $102 million by the end of 2012, while the cost to replace lost power hit $300 million, Edison International said Tuesday in a report on company costs.

The quarterly report showed a total of $402million in combined costs; future costs remain uncertain.

But the manufacturer of the steam generators has repaid $45 million to Edison under a warranty agreement, and Edison has submitted a total of $106 million in invoices, expected to further reduce the repair and inspection total.

The plant has been shuttered for more than a year.

Four steam generators, two for each reactor at San Onofre, were installed between 2009 and early 2011 in a $671 million operation, but a small leak of radioactive gas prompted shutdown of the Unit 3 reactor on Jan. 31, 2012.

Unit 2 already had been taken offline for maintenance.

Inspection of both reactor units revealed unexpected wear among the thousands of metal tubes that carry water heated by the reactors inside the steam generators. The wear was later traced to design flaws in the generators, built by Mitsubishi Heavy Industries in Japan.

Edison has proposed restarting Unit 2, where the wear is less extensive, at 70 percent power; the Nuclear Regulatory Commission has said it could decide whether to allow the restart as soon as late April.

The lower-power restart is expected to eliminate vibrations believed to have caused the unexpected wear.

But the restart plan has faced heavy opposition from activists.

Edison officials hope for restart this summer, said Ted Craver, chairman of Edison International, the parent company of Southern California Edison, which runs the San Onofre plant.

“We are convinced it is safe to run the unit,” Craver told Wall Street analysts during a conference call.